Buggy code:
public class LessCompiler { private static final String COMPILE_STRING = "function<seq2seq4repair_space>doIt(input,<seq2seq4repair_space>compress)<seq2seq4repair_space>{<seq2seq4repair_space>return<seq2seq4repair_space>compile(input,compress)<seq2seq4repair_space>};" ; private static final LessLogger logger = LessLoggerFactory . getLogger ( LessCompiler . class ) ; private URL compileJs = LessCompiler . class . getClassLoader ( ) . getResource ( "META-INF//compile.js" ) ; private URL envJs = LessCompiler . class . getClassLoader ( ) . getResource ( "META-INF//env.rhino.js" ) ; private URL lessJs = LessCompiler . class . getClassLoader ( ) . getResource ( "META-INF//less-2.4.0.js" ) ; private List < URL > customJs = Collections . emptyList ( ) ; private boolean compress = false ; private String encoding = null ; private Function doIt ; private Scriptable scope ; private URL envV8Js = LessCompiler . class . getClassLoader ( ) . getResource ( "META-INF//env.v8.js" ) ; private ScriptEngine v8 ; public LessCompiler ( ) { } public URL getEnvJs ( ) { } public synchronized void setEnvJs ( URL envJs ) { } public URL getLessJs ( ) { } public synchronized void setLessJs ( URL lessJs ) { } public List < URL > getCustomJs ( ) { } public synchronized void setCustomJs ( URL customJs ) { } public synchronized void setCustomJs ( List < URL > customJs ) { } public boolean isCompress ( ) { } public synchronized void setCompress ( boolean compress ) { } public String getEncoding ( ) { } public synchronized void setEncoding ( String encoding ) { } public synchronized void init ( ) { } public boolean initV8 ( ) { } public synchronized String compile ( String input ) throws LessException { if ( ( input == null ) || ( ( input . length ( ) ) == 0 ) ) { return "" ; } if ( ( ( v8 ) == null ) && ( ( scope ) == null ) ) { init ( ) ; } long start = System . currentTimeMillis ( ) ; Context cx = null ; try { Object result ; if ( ( v8 ) != null ) { Invocable invocable = ( ( Invocable ) ( v8 ) ) ; result = invocable . invokeFunction ( "doIt" , input , compress ) ; } else { cx = Context . enter ( ) ; result = doIt . call ( cx , scope , null , new Object [ ] { input , compress } ) ; if ( LessCompiler . logger . isDebugEnabled ( ) ) { LessCompiler . logger . debug ( ( ( "Finished<seq2seq4repair_space>compilation<seq2seq4repair_space>of<seq2seq4repair_space>LESS<seq2seq4repair_space>source<seq2seq4repair_space>in<seq2seq4repair_space>" + ( ( System . currentTimeMillis ( ) ) - start ) ) + "<seq2seq4repair_space>ms." ) ) ; } } String [ ] parts = result . toString ( ) . split ( "\\|MESSAGES\\|" ) ; String messages = ( ( parts . length ) > 1 ) ? parts [ 1 ] : "" ; if ( ( messages . length ( ) ) > 0 ) { LessCompiler . logger . info ( ( "LESS<seq2seq4repair_space>WARNINGS:<seq2seq4repair_space>" + messages ) ) ; } <START_BUG> String css = parts [ 0 ] ; <END_BUG> String errorPrefix = "error:" ; if ( css . startsWith ( errorPrefix ) ) { throw new IllegalStateException ( css . substring ( errorPrefix . length ( ) ) ) ; } return css ; } catch ( Exception e ) { logErrorDetail ( input , e ) ; if ( e instanceof JavaScriptException ) { Scriptable value = ( ( Scriptable ) ( ( ( JavaScriptException ) ( e ) ) . getValue ( ) ) ) ; if ( value != null ) { String msg = extractErrorPointerMessage ( value ) ; throw new LessException ( msg , e ) ; } } if ( e instanceof IllegalStateException ) { throw new LessException ( e . getMessage ( ) , e ) ; } throw new LessException ( e ) ; } finally { if ( cx != null ) { Context . exit ( ) ; } } } public String compile ( File input ) throws IOException , LessException { } public void compile ( File input , File output ) throws IOException , LessException { } public void compile ( File input , File output , boolean force ) throws IOException , LessException { } public String compile ( LessSource input ) throws LessException { } public void compile ( LessSource input , File output ) throws IOException , LessException { } public void compile ( LessSource input , File output , boolean force ) throws IOException , LessException { } private void logErrorDetail ( String input , Exception e ) { } private String extractErrorPointerMessage ( Scriptable value ) { } private String removeFractions ( String in ) { } }

Fix:
String css = ( ( parts . length ) > 0 ) ? parts [ 0 ] : "" ;